A. Technical Field
Small circuits or circuit elements of feature size of the order of a few micrometers or smaller generally undergo one or more lithographic delineation steps in fabrication. One such category of circuits often fabricated in and on epitaxial silicon is known as large scale integration (LSI). Prevalent manufacture is based on sets of discrete masks patterned by means of ultraviolet light, electron beam or other actinic radiation. An alternative approach, known as "direct processing", is based on primary pattern delineation in masking layers affixed directly to the device or circuit during manufacture.
All such processes involve primary or secondary pattern delineation to eventually permit plating, etching or other modification of underlying active material exclusively in bared regions of apertured masking layers.